1. Field of the Invention
This invention relates to methods, compositions and kits for simultaneously detecting one or more analytes such as drugs in a sample.
The clinical diagnostic field has seen a brad expansion in recent years, both as to the variety of materials of interest that may be readily and accurately determined, as well as the methods for the determination. Convenient, reliable and non-hazardous means for detecting the presence of low concentrations of materials in liquids is desired. In clinical chemistry these materials may be present in body fluids in concentrations below 10−12 molar. The difficulty of detecting the presence of these materials in low concentrations is enhanced by the relatively small sample sizes that can be utilized.
Over the last decade, testing for drugs of abuse has become commonplace. This testing is not only for the monitoring of criminal offenders and drug addicts, but employers also use it for the screening of workers. Most multi-analyte assays are heterogeneous, have poor sensitivity and poor dynamic range (2- to 100-fold difference in concentration of the analytes is determined) and some require the use of sophisticated instrumentation.
High volume screening for drugs of abuse is currently carried out commercially by conducting a series of individual homogeneous immunoassays (EMIT or FPIA). A cut off level is set for each drug, which is used to establish whether a particular result will be defined as positive or negative. It is necessary for testing laboratories to handle separate reagent sets and carry out separate assays for each of the commonly abused drugs in every sample. Typically, the presence of as many as six drugs must be determined.
Among those homogeneous assays that have been used commercially or are particularly good candidates for drug screening, EMIT®, CEDIA®, FRAT® and SLFIA have the property of having an increase in signal with an increase in drug concentration. However, because of sensitivity problems or problems intrinsic to these methods, assays for low concentration analytes can have relatively high negative signals, sometimes more than 50% of the maximum possible signals. Combined assays, therefore, show a serious loss in sensitivity. Moreover, induced luminescence assays have decreased signals (fluorescence polarization and chemiluminescence, respectively) with increasing drug concentration and are, therefore, poor candidates for a combined drug assay.
Because of the resultant increase in testing, a market has opened up for “quick “Yes or No” tests.” These are assays that can test qualitatively for drugs of abuse. Many of the “quick tests” which have been described are designed to be used as “on site” assays, [EZ-SCREEN™ (Editek Inc., Burlington, N.C.), ONTRAK™ (Roche Diagnostics Systems, Inc., Branchburg, N.J.), Triage™ (Biosite Diagnostics, San Diego, Calif.) and ONTRAK TESTCUP-5™ (Roche Diagnostic Systems, Somerville, N.J.)] and a few of them are able to test for more than one drug in a single assay (Triage™ and ONTRAK TESTCUP-5™). In these multi-analyte systems, if any one of the tested drugs is over a threshold limit, a positive result is obtained. Such positive results must then be confirmed by an unrelated method.
2. Brief Description of the Related Art
U.S. Pat. No. 5,661,019 (Oh, et al.) discloses trifunctional conjugates having three chemical moieties attached through a spacer moiety.
U.S. Pat. No. 5,567,627 (Lehnen) describes method and composition for the simultaneous and discrete analysis of multiple analytes.
U.S. Pat. No. 5,340,716 (Ullman, et al.) describes an assay method utilizing photoactivated chemiluminescent labels.
Photoactivatable chemiluminescent matrices are described in U.S. Pat. No. 5,709,994 (Pease, et al.).